title: Global transcriptome profiles of Camellia sinensis during cold acclimation.
abstract: BACKGROUND
  Tea is the most popular non-alcoholic health beverage in the world. The tea plant (Camellia sinensis (L.) O. Kuntze) needs to undergo a cold acclimation process to enhance its freezing tolerance in winter. Changes that occur at the molecular level in response to low temperatures are poorly understood in tea plants. To elucidate the molecular mechanisms of cold acclimation, we employed RNA-Seq and digital gene expression (DGE) technologies to the study of genome-wide expression profiles during cold acclimation in tea plants.
  
  
  RESULTS
  Using the Illumina sequencing platform, we obtained approximately 57.35 million RNA-Seq reads. These reads were assembled into 216,831 transcripts, with an average length of 356 bp and an N50 of 529 bp. In total, 1,770 differentially expressed transcripts were identified, of which 1,168 were up-regulated and 602 down-regulated. These include a group of cold sensor or signal transduction genes, cold-responsive transcription factor genes, plasma membrane stabilization related genes, osmosensing-responsive genes, and detoxification enzyme genes. DGE and quantitative RT-PCR analysis further confirmed the results from RNA-Seq analysis. Pathway analysis indicated that the "carbohydrate metabolism pathway" and the "calcium signaling pathway" might play a vital role in tea plants' responses to cold stress.
  
  
  CONCLUSIONS
  Our study presents a global survey of transcriptome profiles of tea plants in response to low, non-freezing temperatures and yields insights into the molecular mechanisms of tea plants during the cold acclimation process. It could also serve as a valuable resource for relevant research on cold-tolerance and help to explore the cold-related genes in improving the understanding of low-temperature tolerance and plant-environment interactions.
authors.affiliation: Tea Research Institute, Chinese Academy of Agricultural Sciences; National Center for Tea Improvement, Key Laboratory of Tea Plant Biology and Resources Utilization, Ministry of Agriculture, Hangzhou 310008, China.
authors.forename: Xin-Chao
authors.initials: XC
authors.lastname: Wang
authors.forename: Qiong-Yi
authors.initials: QY
authors.lastname: Zhao
authors.forename: Chun-Lei
authors.initials: CL
authors.lastname: Ma
authors.forename: Zong-Hong
authors.initials: ZH
authors.lastname: Zhang
authors.forename: Hong-Li
authors.initials: HL
authors.lastname: Cao
authors.forename: Yi-Meng
authors.initials: YM
authors.lastname: Kong
authors.forename: Chuan
authors.initials: C
authors.lastname: Yue
authors.forename: Xin-Yuan
authors.initials: XY
authors.lastname: Hao
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.forename: Jian-Qiang
authors.initials: JQ
authors.lastname: Ma
authors.forename: Ji-Qiang
authors.initials: JQ
authors.lastname: Jin
authors.forename: Xuan
authors.initials: X
authors.lastname: Li
authors.forename: Ya-Jun
authors.initials: YJ
authors.lastname: Yang
mesh_terms: D000064:Acclimatization / Q000235:genetics*; D028241:Camellia sinensis / Q000166:cytology / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D003080:Cold Temperature; D020869:Gene Expression Profiling; D017343:Genes, Plant / Q000235:genetics; D058977:Molecular Sequence Annotation; D009995:Osmosis; D018749:RNA, Plant / Q000235:genetics; D015203:Reproducibility of Results; D017423:Sequence Analysis, RNA; D015398:Signal Transduction / Q000235:genetics
chemical_list: D018749:RNA, Plant